<template>
  <div class="goods-wrap">
    <div class="goods">
      <!-- 左侧的滑动栏目 -->
      <div class="menu-wrapper" ref="menuWrapper">
        <ul>
          <!--current-->   <!--currentIndex-->
          <li class="menu-item" v-for="(good, index) in goods"
              :key="index" :class="{current: currentIndex===index}" @click="clickMenu(index)">
            <span class="text bottom-border-1px">
              <img class="icon" v-if="good.icon" :src="good.icon">
              {{good.name}}
            </span>
          </li>
        </ul>
      </div>

      <!-- 右侧的滑动栏目 -->
      <div class="foods-wrapper" ref="foodsWrapper">
        <ul>
          <!-- 先遍历做外层的主菜单 -->
          <li class="food-list food-list-hook" v-for="(good, index) in goods" :key="index">
            <h1 class="title">{{good.name}}</h1>
            <ul>
              <!-- 在便利内层的子菜单 -->
              <li class="food-item bottom-border-1px" v-for="(food, index) in good.foods"
                  :key="index" @click="showFood(food)">
                <div class="icon">
                  <img width="57" height="57" :src="food.icon">
                </div>
                <div class="content">
                  <h2 class="name">{{food.name}}</h2>
                  <p class="desc">{{food.description}}</p>
                  <div class="extra">
                    <span class="count">月售{{food.sellCount}}份</span>
                    <span>好评率{{food.rating}}%</span>
                  </div>
                  <div class="price">
                    <span class="now">￥{{food.price}}</span>
                    <span class="old" v-if="food.oldPrice">￥{{food.oldPrice}}</span>
                  </div>
                  <div class="cartcontrol-wrapper">

                    <!-- 添加购物车的组件 -->
                    <cart-control :food="food" />
                  </div>
                </div>
              </li>
            </ul>
          </li>
        </ul>
      </div>
      <shopCart />
    </div>
    <!-- 弹出商品详情 -->
    <food :food="food" ref="food" />
  </div>
</template>

<script>

import CartControl from '../../../components/CartControl/CartControl.vue'

import ShopCart from '../../../components/ShopCart/ShopCart.vue'

import Food from '../../../components/Food/Food.vue'

import {mapState} from 'vuex'

import BScroll from 'better-scroll'
export default {
  components: {
    CartControl,
    ShopCart,
    Food
  },
  name: 'ShopGoods',
  data () {
    return {
      tops: [], // 所有右侧分类li标签的top所组成数组
      food: {},
      scrollY: 0 // 右侧滑动的y坐标
    }
  },
  mounted () {
    // 请求 getShopGoods 获得所有的商品信息
    this.$store.dispatch('getShopGoods', () => {
      this.$nextTick(() => {
        this._initScroll()
        this._initTops()
      })
    })
  },
  computed: {
    ...mapState(['goods']),
    /*
      1. 分析出相关的数据
          scrollY: 右侧滑动的y坐标
          tops: 所有右侧分类li标签的top所组成数组
      2. 分析计算逻辑
          tops = [0, 10, 15, 18, 15]
          scrollY =      14, 17, 20
          currentIndex = 1, 2, 3
          scrollY>=top && scrollY<nextTop
      计算属性什么就会执行?: 相关的数据发生了变化
       */
    currentIndex () {
      const {tops, scrollY} = this
      console.log('current scrollY', scrollY)
      let idx = tops.findIndex((top, index) => {
        return scrollY >= top && scrollY < tops[index + 1]
      })
      return idx
    }
  },
  methods: {
    // 初始化滑动组件
    _initScroll () {
      // 左侧滑动栏
      new BScroll('.menu-wrapper')
      // 右侧的滑动栏
      this.right = new BScroll('.foods-wrapper', {
        // startY: -100
        probeType: 1, // 会在滑动(手指触摸)过程中实时派发scroll事件
        /* 作用：better-scroll 默认会阻止浏览器的原生 click 事件。
        当设置为 true，better-scroll 会派发一个 click 事件，我们会
        给派发的 event 参数加一个私有属性 _constructed，值为 true */
        click: true
      })

      // 监听滑动事件
      this.right.on('scroll', (event) => {
        console.log(event.X, event.y)
        this.scrollY = Math.abs(event.y) // 记录 y 坐标值
      })

      // 监视右侧列表的滚动结束
      this.right.on('scrollEnd', (event) => {
        // 获取滚动的y坐标
        console.log('scrollEnd', event.y)
        this.scrollY = Math.abs(event.y)
      })
    },
    // 初始化右边每个li距离顶端的距离数组
    _initTops () {
      let tops = []
      // 找到所有的li
      let lis = this.$refs.foodsWrapper.getElementsByClassName('food-list-hook')
      // 将所有的饿 li 的高度放到 tops 数组中
      tops.push(0)
      let top = 0
      Array.prototype.slice.call(lis).forEach((li) => {
        top += li.clientHeight
        tops.push(top) // 将 li 距离顶端的高度放进去
      })
      this.tops = tops
      console.log('tops[] : ', tops)
    },
    // 点击左边菜单栏
    clickMenu (index) {
      console.log('methods#clickMenu')
      // 立即更新scrollY, 立即让currentIndex重新计算
      this.scrollY = this.tops[index]
      // 让右侧列表平滑滚动到指定位置
      this.right.scrollTo(0, -this.scrollY, 300)
    },
    // 显示点击的food
    showFood (food) {
      // 设置food
      this.food = food
      // 显示food组件 (在父组件中调用子组件对象的方法)
      this.$refs.food.toggleShow()
    }
  }
}
</script>

<style lang="stylus" ref="stylesheet/stylus">
  @import "../../../common/stylus/mixins.styl"
  .goods
    display: flex
    position: absolute
    top: 195px
    bottom: 46px
    width: 100%
    background: #fff;
    overflow: hidden
    .menu-wrapper
      flex: 0 0 80px
      width: 80px
      background: #f3f5f7
      .menu-item
        display: table
        height: 54px
        width: 56px
        padding: 0 12px
        line-height: 14px
        &.current
          position: relative
          z-index: 10
          margin-top: -1px
          background: #fff
          color: $green
          font-weight: 700
          .text
            border-none()
        .icon
          display: inline-block
          vertical-align: top
          width: 12px
          height: 12px
          margin-right: 2px
          background-size: 12px 12px
          background-repeat: no-repeat
        .text
          display: table-cell
          width: 56px
          vertical-align: middle
          bottom-border-1px(rgba(7, 17, 27, 0.1))
          font-size: 12px
    .foods-wrapper
      flex: 1
      .title
        padding-left: 14px
        height: 26px
        line-height: 26px
        border-left: 2px solid #d9dde1
        font-size: 12px
        color: rgb(147, 153, 159)
        background: #f3f5f7
      .food-item
        display: flex
        margin: 18px
        padding-bottom: 18px
        bottom-border-1px(rgba(7, 17, 27, 0.1))
        &:last-child
          border-none()
          margin-bottom: 0
        .icon
          flex: 0 0 57px
          margin-right: 10px
        .content
          flex: 1
          .name
            margin: 2px 0 8px 0
            height: 14px
            line-height: 14px
            font-size: 14px
            color: rgb(7, 17, 27)
          .desc, .extra
            line-height: 10px
            font-size: 10px
            color: rgb(147, 153, 159)
          .desc
            line-height: 12px
            margin-bottom: 8px
          .extra
            .count
              margin-right: 12px
          .price
            font-weight: 700
            line-height: 24px
            .now
              margin-right: 8px
              font-size: 14px
              color: rgb(240, 20, 20)
            .old
              text-decoration: line-through
              font-size: 10px
              color: rgb(147, 153, 159)
          .cartcontrol-wrapper
            position: absolute
            right: 0
            bottom: 12px
</style>
